Bus-bar supports



Sept. 16, 1969 e. 1.. CLAYBOURN BUS-BAR SUPPORTS Filed July 26, 1967FIG. 2 PRIOR ART INVENTOR Glen L Cloybourn BY f WTORNEY United StatesPatent 3,467,766 BUS-BAR SUPPORTS Glen L. Clayhourn, Pittsburgh, Pa.,assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., acorporation of Pennsylvania Filed July 26, 1967, Ser. No. 656,103

Int. Cl. H02g 5/00 US. Cl. 174-100 8 Claims ABSTRACT OF THE DISCLOSUREAn insulating tie member, supporting one or more highvoltage bus bars,has its ends spaced from angle clips attached to side-frame supports bymeans of spacing means, either assuming the form of a standoffinsulator, or a channel-shaped insulating spacing member, andadditionally providing shielding means for relieving the potentialgradient adjacent the inner sheared edge of the angle clip to preventvoltage breakdown.

This invention relates generally to bus-bar supports and, moreparticularly, to improved bus-bar supports in which an insulating tiemember, supporting the one or more bus bars, is spaced from angle clipsto provide vertical insulating surfaces and also to relieve thepotential gradient adjacent the inner edges of the side angle clips.

A general object of the present invention is to provide an improvedsupporting means for bus bars.

A more specific object of the present invention is to provide animproved bus-bar support in which the voltage gradient adjacent the sidesupporting angle clips is relieved and, additionally, a long creepagepath is provided between the ends of the members and the metallic sidesupporting clips.

Still a further object of the present invention is the provision of animproved bus-bar support in which a standoff insulator is interposedbetween the end of the insulating tie member and the side supportingangle clip, together with angular potential gradient shielding means.

Yet a further object of the present invention is the provision of animproved bus-bar supporting means in which channel-shaped insulatingshielding means is employed to space the ends of the tie members to theside angle brackets and additionally to relieve the potential gradient.

In accordance with a preferred embodiment of the invention, theinsulating tie member, which supports the one or more high-voltageinsulating conductors, has its ends secured to standoff insulators,preferably formed of porcelain, the latter being affixed to metallicside angle brackets; and an insulating angular potential gradient shieldis additionally employed to shield the inner sheared edge of the steelangle brackets.

According to another embodiment of the invention, an insulatingchannel-shaped insulating member is employed to not only space the endsof the insulating tie member, but additionally serves a potentialgradient shielding function.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawing, inwhich:

FIGURE 1 illustrates a prior-art bus-bar supporting means which leads todeleterious tracking and carbonization action due to corona formation;

FIG. 2 is an inverted plan view of the upper surface of a typicalprior-art mating tie-member construction in which the tracking andultimate voltage breakdown are readily apparent;

FIG. 3 illustrates an embodiment of the present invention in which astandoff insulator is employed as a Patented Sept. 16, 1969 ice verticalspacing means interposed between the ends of the tie member and theadjacent metallic angle clips; and,

.FIG. 4 is an alternate embodiment of the invention in which aninsulating channel-shaped spacing member is employed to not only spacethe tie member from the side angle clips, but aditionally to provide apotential gradient shielding function.

Referring to the drawing, and more particularly to FIG. 1 thereof, thereference numeral 1 generally designates a tie member, which is used tosupport a plurality, such as three bus bars 2, to side frame members 3.As shown, the tie-member construction may comprise two mating members1a, 1b having solts 4 therein to encompass the three bus bars 2, and areaffixed at their ends 5 to the side-angle bars, or struts 3 by bolts 7.This is a typical prior-art construction, which has led to voltagebreakdown between the high-voltage. bus bars 2 and the grounded sideframe members 3 by a tracking, or treeing action, which occurs on thehorizontal surfaces of the tie members 1a, 1b. It will be noticed thatdue to the horizontal disposition of the tie members 1a, 1b, andaccumlation of salt, dust or other contaminants may occur upon the upperhorizontal surfaces 8 of the tie members 1a, 1b, thereby being conduciveto voltage breakdown.

FIG. 2 shows a slightly alternate prior-art construction 10 in which themating tie members 10a, 1012 have transverse mating slots 11 providedtherein, which again encompass the three bus bars (not shown), and havetheir ends suitably apertured, as at 12, so as to accommodate bolts,which again would be used to become attached to side-angle framemembers, such as the frame member of FIG. 1. It will be noted that thediscoloration and the carbonization 14, as indicated in FIG. 2, leads toa lowering of the dielectric strength of the tie members 10a, 10b, andis conducive to voltage breakdown between the highvoltage bus bars 2 andthe grounded side frame supports 3.

The present invention is directed to the elimination of the flashoverproblem occurring in bus-bar supports by interposing a spacing-memberconstruction 16, which not only leads to a greater creepage path, butadditionally provides a voltage-gradient relieving action, and alsopreferably is vertically disposed, so as not to permit the accumulationof contaminants. As is well known, contaminants tend to accumulate onhorizontal surfaces and. not on vertical surfaces.

With reference to FIG. 3 of the drawing, it will be noted that theinsulating tie member has its end perforated, as at 17, and it isbolted, as by a mounting bolt and washer 18, 19, to the insert 20, whichis provided at the upper end of the standoff insulator 21, whichperferably is composed of porcelain. At the lower end of the porcelainstandoff insulator 21, it will be noted that there is provided a secondinsert 22, which accommodates a mounting bolt 23, which passes throughan insulating angular potential gradient shield 24, and additionallypasses through an aperture 25 provided in the horizontal surface 26 of awelded steel support bracket, or clip 27 suitably affixed to the steelside sheet, or side frame support member 28. As is well known by thoseskilled in the art, in metal-clad switchgear, in which circuit breakersor other equipment is moved into metallic housings or cubicles, it isnecessary to suitably insulatingly support the bus bars from theinterior side wall surfaces of the cubicle. FIG. 3 only shows a portionof such a cubicle construction, the steel side sheet 28 constituting aside wall member of the associated cubicle 29.

It will be observed, with reference to FIG. 3, that the angularinsulating potential gradient shield 24 serves to relieve the potentialstress at the sharp sheared steel edges 30 of the angle bracket 27, andprevents voltage breakdown occurring, due to corona formation, betweenthe grounded angle bracket 27 and the high-voltage insulated conductor2.

Also, with reference to FIG. 3, it will be noted that the verticalsurfaces 21a of the porcelain standoff insulator 21 provideverticalsurfaces, which will tend to remain clean and prevent the accumulationthereon of contaminants, which otherwise would be conducive to voltagebreakdown.

FIG. 4 shows an alternate embodiment of the invention 31 in which aninsulating channel-shaped support and spacing member 32 is provided,being aflixed by bolts 33 to the ends of the insulating tie member 1,and additionally being-affixed by 'bolts 34 to the mounting holesprovided in the horizontal surface 26 of the associated welded steelsupport bracket 27. Again, the sharp edges, as at 30, are-shielded bythe adjacent surface portion 32a of the channel-shaped supporting member32, which will prevent voltage breakdown. Corona formation is conduciveat.sharp edges, and unless the voltage condition is relieved by theinterposition of a high dielectric material 32, voltage fiashover mayoccur. By the provision of the insulating channel shielding andsupporting member 32, which is preferably made of a molded glasspolyester material, the voltage condition is relieved. The provision ofvertical insulation surfaces 32b will minimize the collecting of dustand/or contaminants or moisture on the surfaces.

From the foregoing description it will be apparent that an object of thepresent invention is to provide an increased creepage path to groundover a porcelain insulating surface 21a, or an insulating channel-shapedmember 32 for the high-voltage conductor tie-support member 1,especially suitable in confined unit assemblies. This supportingassembly 16, 31 also makes it possible to install a glass polyestergradient shield at the highly stressed ground plane area. Flatinsulation surfaces, that have collected dust and/or contaminants, suchas salt will introduce a low-resistance path to ground when operating athigh voltage under high humidity conditions. It is, therefore, verydesirable to introduce, or provide a vertical porcelain surface 21a inthe tie-support assembly 16, as shown in FIG. 3, that will dry off veryrapidly due to leakage current, and will not carbonize or track.Additionally, in confined assemblies, it is necessary to provide aninsulation shield 24, 32 between the high-voltage insulated conductor 2and the sharp steel edges of the tie support 27. This shield 24, 32 isto provide an improved dielectric gradient at the area during switchingand lightning surges. Moreover, the constructions indicate a novelmethod of getting an elongated vertical creepage surface for leakageresistance, and additionally providing a voltage gradient assembly,which shields the sharp steel edges 30 of the side angle clips 27. Theprovision of vertical insulation surfaces 21a, 32b will minimize thecollecting of dust and/or contaminants or moisture on the surfaces, andprovide a high resistance leakage path to ground.

The construction illustrated in FIG. 4 illustrates a simple and novelmethod of getting an elongated vertical creepage surface and a shieldingmember 32 all provided by one molded insulation member, preferablyformed of glass polyester material.

I claim as my invention:

1. A bus-bar supporting structure comprising, in combination, at leastone high-voltage bus bar, a horizontally disposed insulating tie memberaffixed to said high-vol- 4 v tage bus bar and serving to rigidlysupport the same in operative position, vertically disposed metallicside supporting means having an angular metallic support member securedthereto, vertically disposed insulating supporting means spacing theouter end of said horizontally disposed insulating tie member verticallywith respect to said angular support member, and said verticallydisposed insulating supporting means having an insulating voltagegradient shield plate portion as a component part thereof shielding theinner edge of said angular support member from the high-voltage bus barto minimize the formation of corona.

2. A bus-bar supporting structure comprising, in combination, a leastone high-voltage bus bar, a horizontally disposed insulating tie memberaffixed to said high-voltage bus bar and serving to rigidly support thesame in operative position, vertically disposed metallicside supportingmeans having an angular metallic support member secured thereto, avertically arranged standoff insulator spacing the outer end of saidhorizontally disposed insulating tie member vertically with respect tosaid angular support member, and said vertically arranged standoffinsulator having an insulating voltage gradient shield ('24) shieldingthe inner edge (30) of said angular support memher from the high-voltagebus bar to minimize the formation of corona.

3. The combination of claim 2, wherein the insulating voltage gradientshield is an insulating angular member (24) and the inner'end (30) ofthe metallic angular support member is adjacent the inner apex portionof the insulating angular member (24) and shielded thereby.

4. The combination of claim 3, wherein the standoff insulator isporcelain.

5. The combination of claim 2, wherein the standoff insulator isporcelain.

6. A bus-bar supporting structure comprising, in combination, at leastone high-voltage bus bar, a horizontally disposed insulating tie memberafilxed to said high-voltage bus bar and serving to rigidly support thesame in operative position, vertically disposed metallic side supportingmeans having an angular metallic support member secured thereto, avertically arranged insulating channel member (32) spacing the outer endof said horizontally disposed insulating tie member vertically withrespect to said angular support member, and said vertically arrangedinsulating channel having an insulating voltage gradient shield portion(32b) shielding the inner edge (30) of said angular support member fromthe high-voltage bus bar to minimize the formation of corona.

7. The combination of claim 6, wherein the inner end of the metallicangular support member is disposed in the bight portion of theinsulating channel member (32) and electrically shielded thereby. I

8. The combination of claim 7, wherein the insulatin channel member isformed of glass polyester.

References Cited UNITED STATES PATENTS 4/1965 Gallant et al 174-171 X10/1967 Olashaw 31712O U.S. c1. X.R. 174-140

